Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
Which of the following is a common laboratory indicator for bases?
Methyl orange
Phenolphthalein
Bromothymol blue
Litmus
Correct answer is B
Phenolphthalein is a common laboratory indicator used to detect the presence of bases in a solution. In its basic form (pH > 8.3), it turns pink or purple, indicating the presence of a base.
What is the maximum number of electrons that can occupy the second energy level (n=2)?
2 electrons
18 electrons
8 electrons
32 electrons
Correct answer is C
The correct answer is (b). The second energy level (n=2) can hold a maximum of 8 electrons. It consists of two subshells, 2s and 2p, which can hold 2 and 6 electrons, respectively.
Which of the following statements is true for strong electrolytes?
They do not conduct electricity in the molten state
They completely dissociate into ions in solution
They are non-polar substances
They partially dissociate into ions in solution
Correct answer is B
They completely dissociate into ions in solution. Strong electrolytes are substances that fully dissociate into ions when dissolved in water or melted. As a result, they produce a high concentration of ions in the solution, allowing for efficient electrical conductivity.
24
16
8
32
Correct answer is C
The atomic number of an element is equal to the number of protons, which in this case is 8. The mass number is the total number of protons and neutrons, which is 16. To find the number of neutrons, we subtract the atomic number from the mass number:
Number of neutrons = Mass number - Atomic number
Number of neutrons = 16 - 8
Number of neutrons = 8
So, the element has 8 neutrons.
The boiling point is always higher than the melting point
The melting point is always higher than the boiling point
The melting and boiling points are always the same for all substances
The melting and boiling points can vary depending on the substance
Correct answer is D
The melting and boiling points are specific physical properties of each substance and can vary depending on the nature of the substance. Different substances have different melting and boiling points, which are determined by the strength of the intermolecular forces and the molecular structure of the substance.
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